Shipboard antenna system



.March 24, 1936. J. REBOTIER SHIPBOARD ANTENNA SYSTEM Filed May 7, .1934

INVENTOR JEAN 195807715? ATTORNEY Patented Mar. 24, 1936 UNETED STATESSHIPBOARD ANTENNA SYSTEM Jean Rebotier, Paris, France, assignor toOompagnie Generale de Telegraphic Sans Fil, a

corporation of France Application May 7, 1934, Serial No. 724,316 InFrance May 18, 1933 4 Claims.

The present invention has for its object the compensation of the effecton the control of antennas for Wireless telegraphy installed on board ofships, produced by the rolling of the ships.

It is actually known that the rolling causes upon ships a variation ofthe antenna capacity and that consequently a periodic detuning isproduced of the control of the transmitting and receiving apparatuscoupled to this antenna. This results in periodic variations of theintensity of the transmitting or receiving signals.

According to the invention this detuning is avoided by means of acompensating organ whose functioning is controlled by the same action,the influence of which is intended to be corrected, that is to say, bythe inclination of the ship. Such action will be obtained for instance,by means of a pendulum or gyroscope.

The compensating organ proper will be very easily obtained by means of avariable condenser or a variable self inductance connected in series orin parallel to the antenna, or by means of circuits coupled to thelatter.

The invention will be more clearly understood by referring to theaccompanying drawing, in which Figure 1 illustrates a section through aship which is ofi its normal vertical position;

Figure 2 is a section of a variable condenser wherein compensation iscontrolled by means of a pendulum;

Figure 3 is a section of a variable condenser wherein the pendulum formsthe movable plate element of the condenser.

These figures shown simply as a matter of indication without intentionof thereby limiting the invention, will facilitate a properunderstandingof the principle of the invention.

Figure 1 shows at N a ship, whose antenna A, assumed to be vertical ifrolling does not occur, moves, as a result thereof, into aninstantaneous inclination oz. The apparent antenna capacity is shown atC in dotted lines. It is obvious that this capacity is a minimum if theantenna is in a vertical position and that it increases with theinclination of the ship in accordance with a law depending upon theshape of the antenna.

Figure 2 shows the manner in which the compensation can be obtained bymeans of a variable condenser controlled by a pendulum. In this figure land 2 represent the two armatures of the condenser and 3 the pendulum.The armature l is fixedly secured to the ship thereby following theinclination a; the armature 2, on the contrary, is maintained in thevertical position by the pendulum. It will thus be readily seen that inthis manner a capacity is obtained which is a maximum when theinclination is zero, and which decreases with increasing inclination.

Figure 3 shows a preferred embodiment of the invention whereby thependulum proper forms one of the armatures 2 of the condenser. The otherarmature I will be formed for instance by two metallic plates fastenedto the Walls of a container, containing an insulating liquid, assuringthe damping of the oscillations of the pendulum.

It is evident that the profile of the armatures l and 2 can be so shapedthat a law of determined variation is obtained by which the variationsof the antenna capacity C can be exactly compensated. In order to arriveat the simplest case it could be supposed that the condenser is mountedin parallel with the antenna capacity. In the similar case it, suificesthat, in order to maintain the tuning of the control means, that the sumof the two capacities remains constant.

As is obvious to anyone versed in the art, other laws of variation orother relations between these capacities will be employed, if othercircuits are utilized. For instance, the variable condenser of Figures 2and 3 could be placed in series to the antenna instead of beingconnected in parallel thereto and these elements could be placed incircuits indirectly coupled to the antenna. As above indicated, itshould also be understood that the variable condenser could be replacedby a variable self inductance or other elements permitting the sameresult.

Finally it should be understood that the pendulum can be replaced by agyroscope or any other suitable stabilizing element.

I claim:

1. A shipboard antenna circuit comprising an aerial and a variabletuning element, and means for automatically adjusting the said tuningele- 40 ment so that the proper frequency of the antenna circuit remainsconstant, said means being controlled by the rolling of the ship.

2. A shipboard antenna circuit comprising an aerial and a variablecondenser connected therewith, and means controlled by the rolling ofthe ship for automatically adjusting the said condenser so that theproper frequency of the antenna circuit remains constant.

3. A shipboard antenna. circuit comprising an aerial and a variablecondenser connected therewith, an armature of this condenser beingfixedly mounted relatively to the ship and a second armature beingpivotally mounted so as to remain by the weight action in a constantposition with respect to the vertical line when the ship rolls, the saidarmatures being so shaped that the antenna circuit capacity remainsconstant during, the rollmg.

4. A shipboard antenna circuit comprising an aerial and a. variablecondenser connected therewith, an armature of this condenser beingfixedly and a second armature being pivotally mounted with respect tothe ship, a pendulum attached to the said second armature, and meanscomprising a predetermined armature shape for maintaining the antennacircuit capacitance constant irre- 5

